Consider adding a context to bindings?

[surilindur]

Consider adding a context to bindings?

[maartyman]

An important consideration is to also alter the @comunica/jest to take into account the context when comparing two bindings.

[github-actions]

Thanks for the suggestion!

[rubensworks]

We could probably indeed directly use the IContext interface, and add it as a context field to bindings.

I guess we'll want the context to be only assignable during creation of the bindings? This will require us to go beyond the bindings factory interface of RDF/JS.

Another question is how to handle joins, where 2 bindings are merged (see the merge functions). We may want to require the caller of the merge function to explicitly say how the contexts of 2 bindings should be merged, as there may not be a generic way that is good for all cases.

[maartyman]

In the current version of incremunica (an incremental version of comunica that can process both additions and deletions) I added a diff boolean to the Bindings class to define if a Binding has been deleted or added. A context field for the bindings as described here could perfectly allow for this functionality without the need to change this core comunica package.

Indeed, when merging two bindings, these contexts need to be combined. In my case, if either one of the bindings has a negative diff (meaning it has been deleted) the resulting merge binding has to have a negative diff too (logical and). (At this moment, this has not been correctly implemented in the master branch of incremunica)

[rubensworks]

It sounds like we may want to introduce some kind of merge-handlers for bindings context keys, which define what to do when specific context keys are merged. Perhaps we could even introduce a new bus for this.